Only a month from election day and almost 20 years into Mitt Romney's political career, the question is still being asked.

Is it Moderate Mitt, the governor of Massachusetts who once championed abortion rights and enacted a state-administered health insurance plan? Or is it Severely Conservative Mitt, the presidential candidate who battered rivals on the right by calling for deeper tax cuts and tougher immigration laws?

Last week, based on Romney's soul-of-sweet-reason performance in his debate with President Obama, it was tempting to conclude that Moderate Mitt was back.

In the Denver debate, Romney polished the rough edges off some of the positions he held while he was running in that severely conservative GOP primary campaign. He no longer seeks a "tax cut," he said, at least not for the wealthy — merely "tax relief." He still wants to repeal Obama's healthcare law, but he also wants to keep provisions that are popular. He's not against regulating financial markets, only "excessive regulations." He even promised not to cut federal spending on education, a break from the orthodox GOP view that education spending is too high.

That was "the real Romney," crowed former GOP strategist Mike Murphy, who worked on Romney's 2002 campaign for governor. "The Mitt we saw out there … was finally free of the duct tape of the Republican base politics to get out and be the pragmatist he is."

Well, maybe. A closer look suggests that Romney's move toward the center is a matter of tone and emphasis more than substance. It took Obama by surprise, and it gave Romney a new chance to make his case to voters in the center — all of which made it a success for the GOP campaign. But down in the details, there was less change in Romney's positions than met the ear, and his campaign insisted that he didn't say anything substantively new at all.

On taxes, Romney rebutted Obama's charge that he is seeking a $5-trillion tax cut for the wealthy, saying, "I'm not going to reduce the share of taxes paid by high-income people." That has been his position for some time, but during the GOP primary campaign he put his emphasis in a different place. "We're going to cut taxes on everyone across the country by 20%, including the top 1%," he said then.

The problem, of course, is that Romney's tax proposal promises many things — lower tax rates, fewer tax deductions and no net change in federal revenue — but the candidate has never provided enough details to show how all those things can work. Obama and his allies have seized on the cut in tax rates to charge that the plan would benefit the wealthy at the expense of everyone else; Romney says he won't let that happen, but he doesn't say how beyond asserting that economic growth would solve the problem.

There's no way to settle that argument. But on a tax issue that's arguably more important, the two candidates' positions were unchanged. Obama still wants to increase taxes on high-income taxpayers to help reduce the federal deficit; Romney still firmly rejects increasing taxes on anyone.

On healthcare, Romney said he considers the insurance law he passed in Massachusetts "a model for the nation, state by state" — meaning he still thinks healthcare should be handled at a state level; that's not a change. And he said he wants to keep the most popular provisions of Obama's healthcare law, including its guarantee that insurance will cover preexisting conditions — but his plan guarantees that only to people who already have health insurance, a provision that's in federal law now.

On education, Romney surprised some conservatives during the debate by saying, "I'm not going to cut education funding." That seemed to conflict with his own policy paper on education, which called Obama's education spending excessive and said, "Flooding colleges with federal dollars only serves to drive tuition higher." But campaign aides last week insisted that Romney had never formally proposed cutting education spending.

The politics of Romney's change in tone was straightforward. In the final weeks of a general election campaign, he needs to appeal to voters in the center. The wonder is that his apparent turn toward the middle didn't come earlier. After all, one of his top aides promised after Romney won the primary that the campaign would start over, "almost like an Etch-A-Sketch."

But notice that those who know Romney best, like Murphy, don't use the word "moderate" to describe him. The adjective they prefer is "pragmatic" — as in "pragmatic conservative."

On the substance of his positions, Romney's die is cast. He remains steadfast against raising taxes, even to help reduce the deficit. He remains intent on repealing Obama's healthcare law, even without a full-scale alternative to propose in its place.

History suggests that presidents take their positions and promises seriously, and they take their political lives into dangerous territory if they don't. That's why George H.W. Bush got into trouble when he broke his promise never to raise taxes. It's why Barack Obama plowed ahead toward a big economic stimulus package and an ambitious healthcare law, even when it became clear that his wish for post-partisan government would be a casualty.

Last week, Romney took a half-step toward the center, a move dictated by the needs of a faltering presidential campaign. But it didn't change his core positions; he's still a conservative.